Re: Comet Machholz easy object, worth looking for

From: David Nakamoto (res07oeg_at_verizon.net)
Date: 12/20/04 

Date: Mon, 20 Dec 2004 07:28:11 GMT

Just a posting from the Griffith satellite Observatory - last Saturday the
18th lots of us saw it. It was not visible in anything less than an 8*50
finder, and even then it was just visible in a scope that small. It was a
bluish green fuzzy star. Scopes from 80mm to 355mm (14-inches) were used.
Same lack of any details except the comet got a bit brighter in the larger
apertures of course. My own CCD images taken on an MX916 with 2x2 binning
and 60sec exposures through a 127mm f/12 Mak showed the same view with no
tail. Oh well, there's always next month. 

-- 
   Sincerely,
   --- Dave
----------------------------------------------------------------------
It don't mean a thing
    unless it has that certain "je ne sais quoi"
               Duke Ellington
----------------------------------------------------------------------
"canopus56" <canopus56@yahoo.com> wrote in message 
news:1103513865.695176.58910@c13g2000cwb.googlegroups.com...
> Richard Carlson wrote:
>> I attempted to view it from light polluted skys here in Salt Lake
> City,
>> Ut. . Is it visible in a pair of 7X50's ?
>
> At 20041219 8:30 UTC, the comet was 1/2 deg. south east of HD27487.  To
> find the comet between now and 12/23/2004,  I recommend finding omi1 &
> omi2 Eri.  Scan south to about 1 1/2 degs south and 1 deg east of 39
> Eri. The comet should be on this track until it crosses omi1 & omi2 Eri
> on 12/23.
>
> The next moonless sky time frame begins December 31, 2004 through
> January 12, 2005.
>
> Rough finder charts were plotted using the Minor Planet Center
> ephemerides service. <<
> http://cfa-www.harvard.edu/iau/Ephemerides/Comets/index.html >>
> These charts are available at:
>
> http://members.csolutions.net/fisherka/astronote/finder/
>
> Overview 70 deg finder to 1/10/2005 with Moon phase and transit notes
> http://members.csolutions.net/fisherka/astronote/finder/CometC2004Q270degTo1_10.gif
>
> 25 deg finder with Lep orientation - good through 12/23/2004
> Stars to mag 10
> http://members.csolutions.net/fisherka/astronote/finder/CometC2004Q2Lepv10to1223.gif
>
> 25 deg finder with Eri orientation - good through 12/27/2004
> Stars to mag 10
> http://members.csolutions.net/fisherka/astronote/finder/CometC2004Q2Eriv10to1227.gif
>
> Moon blocking chart to 2/3/2005
> Stars to mag 5
> http://members.csolutions.net/fisherka/astronote/finder/Comet%20C2004Q2Moonto2_3.gif
>
> Ephemerides can be found at:
>
> http://cfa-www.harvard.edu/iau/Ephemerides/Comets/index.html
> http://ssd.jpl.nasa.gov/cgi-bin/eph
>
> The following is my observer report from the Unita Mtns, east of Salt
> Lake City.  A rough sketch of what I saw is at:
>
> 20041217 8:30 UTC 28x 1.25 deg TFOV
> http://members.csolutions.net/fisherka/astronote/observed/C2004Q2/20041217_Machholz_Drawing.gif
>
>
> =============================
> Comet Machholz obs. report
>
> Begin: 20041217 7:29 UTC | 20041216 11:23PM Local Time (MST)
> End: 20041217 8:45 UTC | 20041217 0:45AM Local Time (MST)
>
> Supplement: 20041219 8:30 UTC | 20041219 0:30AM Local Time (MST)
>
> By: canopus56@yahoo.com
>
> Location:
> North Fork Winter Trailhead Parking Lot
> (Off Mirror Lake Highway,
> approx. 12 miles east of Kamas, Utah)
> 40 deg 35.75'N, 111 deg 5.78'W
> Elevation: 7500 ft.
> Temp: 4 deg C
>
> Target:
> Comet C/2004 Q2 (Machholz) was at approx. local alt 25 deg (hand
> measured), azm transiting on meridian.
>
> Limiting magnitude:
> ZLM: 6.2 per IMO Limiting Magnitude Area 2 (Perseus) (15 stars)
> NELM at Machholz: 6.0 per IMO Limiting Magnitude Area 22 (Lep) (14-15
> stars)
>
> Seeing:  Antoniadi II; Pickering 7-8 Bortle: 2
>
> Observed with:
>
> Scope -
> 6" Newt 1120mm fl. Dob
>
> Lenses -
> 40mm - 28x 1.25 TFOV
> 30mm - 37x
> 15mm - 75x
> 9mm - 124x
> 12mm graduated reticule - 93x
>
> Other -
> 8 x 35 Binoculars
>
> Rough sketch:
>
> 20041217 8:30 UTC 28x 1.25 deg TFOV
> http://members.csolutions.net/fisherka/astronote/observed/C2004Q2/20041217_Machholz_Drawing.gif
>
> Comments:
>
> After initially locating this comet in the early morning hours of
> December 16, local time, low in the extinction zone, I decided to try
> again from a truly dark skies site in the Unita Mountains.  Arrival at
> the observing point was timed for the comet's transit and the setting
> of the Moon.
>
> The comet's magnitude is probably between 5.0-5.5, as reported by ICQ
> observers, but no attempt was made to estimate magnitude during this
> session  using the in/out method due to the cold weather.
>
> Currently the comet is passing through Eri.  Because of the lack of
> bright stars in Eri, location of this fast-moving comet was more
> difficult than expected.  Initially I confused it with 53 Eri.   Until
> the comet reaches omi1-omi2 Eri around December 23,  just look for the
> brightest object south of omi1-omi2 Eri, but above the declination of
> gam Eri.
>
> Unlike other comments seen in recent years, Comet Machholz is
> distinguished by its lack of an easily discernible tail.  The 1-2 deg
> extended wispy ion tail seen in astrophotographs posted on the web was
> not seen, probably due to the small aperature size used, e.g. -
>
> http://antwrp.gsfc.nasa.gov/apod/ap041213.html  (aperature not stated)
> http://galaxyphoto.com/temp/jw_comet12_14_.jpg  (with a 12" Schmidt)
>
> Nonetheless, at low magnification (28x), it is a subtle and beautiful
> object to follow.  With six inches of aperture a faint bow shockwave
> could be seen. The shockwave had a slight brightness above the
> background sky brightness. (It appeared similar to a faint nebula, like
> the California nebulae with a hydrogen filter.)   The bright central
> coma is embedded in the shockwave.  See drawing.  The ability to see a
> bowwave was probably a result of very dark skies at the observing site.
>
>
> Low magnification (40mm-28x or 30mm-37x) was the most effective.
>
> Computed size from a visual estimate in the 40mm lens at 28x ( without
> a reticule ) for the 1/2 brightness limit - the coma diameter -  (the
> outer circle in the figure) was 10.5 arcminutes.  This is consistent
> with the most recent International Comet Quarterly Reports. <<
> http://cfa-www.harvard.edu/icq/CometMags.html >>
>
> Every five to ten seconds, a bright extended glint and/or a point glint
> could be seen within the center of the bright coma.  The averted image
> impression was one of a tiny hourglass shape; however, this was  visual
> impression only and no definite detection occurred.
>
> An initial measurement using the 12mm graduated reticule lens was
> botched but was repeated on 20041219 8:30 UTC. (I'm still working
> through the math on the angular size of the smaller and brighter
> central coma seen at 93x.)
>
> For you high-end scope users at there,  6" of aperature was too dim at
> 90x.  You really need more aperature to see anything at that power.
>
> When driving back to Salt Lake City, I briefly stopped on, East Canyon
> Highway below Little Mountain and above East Canyon Reservoir, to check
> the visibility of the comet in urban skies.  The comet was detectable
> from East Canyon, although it was more difficult to locate because of
> the relative lack of guide stars.  Similarly, I could locate the comet
> using 10x 50 binoculars in the city, but only because I had previously
> located the comet at a dark skies site. It was visible only in the
> early morning hours when the city lights were low. In an urban sky, it
> appears only as a faint fuzzy brightness above the urban background sky
> brightness. When city lights are brighter in the early evening hours
> (7:00-8:00 local time) of 12/18, for example, I could not see it.  As
> the comet approaches omi1 Eri around December 23, locating the comet
> under an urban or suburban-rural sky should be less difficult due to
> the presence of guide stars.
>
> Although the Moon increasingly will wash out the sky through Jan. 3rd,
> 2005, wide-field astrophotographers should have a good day around Jan.
> 8, when the comet passes with a few degrees of the Pleiades.  The comet
> is predicted to reach its maximum brightness beginning around Jan. 3rd
> and continuing through Jan. 12. There will be an early evening
> observing window around Jan. 8 before the Moon rises.
>
> All in all, this is a great comet and is worth driving to a dark skies
> site to see, at least once through Jan. 12.
>
> - Canopus56
>
> P.S. - I'm not quite sure what causes a wispy "ion" trail as opposed to
> the "streak" tails I have seen on previous comets.  Any guesses?
>

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